JP2619892B2 - Precious metal recovery method - Google Patents
Precious metal recovery methodInfo
- Publication number
- JP2619892B2 JP2619892B2 JP409088A JP409088A JP2619892B2 JP 2619892 B2 JP2619892 B2 JP 2619892B2 JP 409088 A JP409088 A JP 409088A JP 409088 A JP409088 A JP 409088A JP 2619892 B2 JP2619892 B2 JP 2619892B2
- Authority
- JP
- Japan
- Prior art keywords
- noble metal
- iodine
- waste liquid
- gold
- noble
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は貴金属の回収方法に関するものである。The present invention relates to a method for recovering precious metals.
（従来の技術とその問題点） ヨウ素を含む貴金属含有廃液は、貴金属をヨウ素を含
むエッチング液でエッチングしたりヨウ素溶解液で溶解
する工程より排出され、半導体産業や貴金属に関連する
事業所など多岐にわたっている。貴金属は高価で稀少な
材料であるので、こうしたヨウ素を含む貴金属含有廃液
から貴金属を回収することは非常に重要なことである。(Conventional technology and its problems) Waste liquid containing precious metal containing iodine is discharged from the process of etching precious metal with an etching solution containing iodine or dissolving with an iodine dissolving solution. Over. Since noble metals are expensive and scarce materials, it is very important to recover noble metals from such noble metal-containing waste liquids containing iodine.
こうしたヨウ素を含む貴金属含有廃液より貴金属を回
収するには、ヒドラジンや水素化ホウ素ナトリウムなど
の還元剤により貴金属を還元析出させるのが一般的であ
るが、ヨウ素を含む貴金属含有廃液にふくまれている遊
離ヨウ素成分（I2及びI3 -）をすべて分解した後でない
と貴金属が析出してこないので多量の還元剤を使用しな
いと貴金属を回収することができないといった問題点が
あった。In order to recover a noble metal from a noble metal-containing waste liquid containing iodine, the noble metal is generally reduced and precipitated with a reducing agent such as hydrazine or sodium borohydride, but this is included in the noble metal-containing waste liquid containing iodine. Since noble metal does not precipitate unless all free iodine components (I 2 and I 3 − ) are decomposed, there is a problem that the noble metal cannot be recovered unless a large amount of reducing agent is used.
（発明が解決しようとする問題点） 本発明はこうした問題点に鑑みてなされたもので、遊
離ヨウ素を含む貴金属含有廃液より貴金属を回収するに
際し、遊離ヨウ素成分の分解に多量の還元剤を必要とし
ない貴金属の回収方法を提供せんとするものである。(Problems to be Solved by the Invention) The present invention has been made in view of such problems, and when recovering a noble metal from a noble metal-containing waste liquid containing free iodine, a large amount of a reducing agent is required to decompose the free iodine component. And a method of recovering noble metals.
（問題点を解決するための手段） 上述のごとく本発明による貴金属の回収方法は、遊離
ヨウ素を含む貴金属含有廃液より貴金属を回収するに際
し、該遊離ヨウ素を含む貴金属含有廃液のpHを12以上の
強アルカリ性として遊離ヨウ素をヨウ素酸イオンに変換
してから、化学還元剤及び／または電解により貴金属を
析出させて貴金属を回収することを特徴とするものであ
る。(Means for Solving the Problems) As described above, the method for recovering a noble metal according to the present invention, when recovering a noble metal from a noble metal-containing waste liquid containing free iodine, adjusts the pH of the noble metal-containing waste liquid containing free iodine to 12 or more. The method is characterized in that free iodine is converted to iodate ions as strong alkali, and then a noble metal is precipitated by a chemical reducing agent and / or electrolysis to recover the noble metal.
（作用） 以下本発明の作用についてのべる。(Action) The action of the present invention will be described below.
ヨウ素を含む貴金属含有廃液としては、半導体産業な
どで貴金属のエッチングに使用されるヨウ素エッチング
液や、貴金属化合物や貴金属の回収、精製に伴う廃液な
どがある。含まれる貴金属としては、金、銀、白金、パ
ラジウムなどがあり、稀にはこの他の貴金属がふくまれ
ている。Examples of the noble metal-containing waste liquid containing iodine include an iodine etching solution used for etching a noble metal in the semiconductor industry and the like, and a waste liquid accompanying recovery and purification of a noble metal compound and a noble metal. The noble metals contained include gold, silver, platinum, palladium and the like, and rarely include other noble metals.
該ヨウ素を含む貴金属含有廃液のpHを12以上の強アル
カリ性とすると、ヨウ素を含む貴金属含有廃液にふくま
れている貴金属を溶かす能力を有する遊離ヨウ素成分
（I2及びI3 -）は、ヨウ素の不均化反応によりヨウ素酸
イオンとヨウ素イオンとになり（１式）、 3I2＋6OH-→IO3 -＋5I- １式 強アルカリ性であることも関与して貴金属を溶かす能
力を失うとともに、金が金属金となって析出する。（２
式）。Assuming that the pH of the noble metal-containing waste liquid containing iodine is strong alkalinity of 12 or more, the free iodine components (I 2 and I 3 − ) having the ability to dissolve the noble metal contained in the noble metal-containing waste liquid containing iodine, the disproportionation reaction becomes and iodate ion and an iodine ion (1 formula), 3I 2 + 6OH - → IO 3 - + 5I - with 1 it is formula strongly alkaline also involved lose the ability to dissolve precious metals, gold It becomes metallic gold and precipitates. (2
formula).
2AuI4 -＋6OH-→2Au＋IO3 -＋7I- ２式 貴金属含有廃液のpHが12以下であると１式の反応が起
こらず、貴金属を酸化し溶かす能力のある遊離ヨウ素成
分が該廃液中に存在してしまう。金以外の貴金属は、ほ
とんどがまだ該廃液中に含まれており、また未反応の金
も該廃液中に存在するので、さらに化学還元剤及び／ま
たは電解により貴金属を析出させて回収する。2AuI 4 − + 6OH − → 2Au + IO 3 − + 7I − 2 Formula If the pH of the noble metal-containing waste liquid is 12 or less, no reaction occurs, and a free iodine component capable of oxidizing and dissolving the noble metal is present in the waste liquid. Would. Most of the noble metals other than gold are still contained in the waste liquid, and unreacted gold is also present in the waste liquid. Therefore, the noble metal is further precipitated and recovered by a chemical reducing agent and / or electrolysis.
ヨウ素を含む貴金属含有廃液のpHを強アルカリ性にす
るには、適当なアルカリ（水酸化ナトリウム、水酸化カ
リウムなど）を加えれば良く、固体で加えても、液体で
加えても良い。To make the pH of the noble metal-containing waste liquid containing iodine strong alkaline, an appropriate alkali (such as sodium hydroxide and potassium hydroxide) may be added, and it may be added as a solid or a liquid.
化学還元剤としては、前述のヒドラジンや水素化ホウ
素ナトリウムなどのほかに、マグネシウムやアルミニウ
ム、亜鉛末などの金属還元剤などの多くのものがある
が、還元する該貴金属含有廃液のpHを12以上としてある
ので、その条件で貴金属を還元する能力のあるものなら
ば特に問題はない。また電解により陰極に貴金属を析出
させてもよい。As the chemical reducing agent, in addition to the above-mentioned hydrazine and sodium borohydride, there are many such as magnesium, aluminum, and metal reducing agents such as zinc powder, and the pH of the noble metal-containing waste liquid to be reduced is 12 or more. Therefore, there is no particular problem as long as it is capable of reducing the noble metal under the conditions. Also, a noble metal may be deposited on the cathode by electrolysis.
pH12以下の条件では、ヨウ素を含む貴金属含有廃液に
含まれている遊離ヨウ素成分（I2及びI3 -）を、全て分
解した後でないと貴金属が析出してこないが、本発明で
は、予めpH12以上の強アルカリ性に調整してあるので、
遊離ヨウ素成分は、２式に従いヨウ素酸イオンとなり貴
金属を酸化する能力を失う。また酸化還元電位が変化
し、貴金属が析出してこないとヨウ素酸が分解されなく
なるので、還元剤を加えた際は、貴金属の析出の後、ヨ
ウ素酸の分解反応がおこる。実際の反応では、貴金属の
析出と共にヨウ素酸の分解も一部おこるが、従来のよう
に全ての遊離ヨウ素成分を分解させる必要がなく、本発
明では全てのヨウ素酸塩が分解されなくても貴金属を析
出、回収することができるので、薬品効率や電気効率が
向上する。Under the condition of pH 12 or less, noble metal will not be deposited unless all free iodine components (I 2 and I 3 − ) contained in the noble metal-containing waste liquid containing iodine are decomposed. Because it is adjusted to the above strong alkaline,
The free iodine component becomes iodate ions according to the two formulas and loses the ability to oxidize noble metals. In addition, the oxidation-reduction potential changes, and iodic acid is not decomposed unless the noble metal is precipitated. Therefore, when a reducing agent is added, the decomposition reaction of iodic acid occurs after the precipitation of the noble metal. In the actual reaction, the iodic acid is partially decomposed together with the precipitation of the noble metal.However, it is not necessary to decompose all the free iodine components as in the past, and in the present invention, the precious metal is not decomposed even if not all the iodate is decomposed. Can be deposited and recovered, thereby improving the chemical efficiency and the electrical efficiency.
還元剤の使用に伴pHが下がったりすることがあり、12
以下になると薬品の使用量が増加する。従って貴金属の
還元、析出は12を下回らないpHが良く、好ましくは12.5
〜14.5の範囲の条件下で行い、その条件はアルカリ規定
度に換算すると0.03〜3Nである。The pH may decrease with the use of reducing agents,
Below this, the amount of chemicals used increases. Therefore, noble metal reduction, precipitation is good pH not less than 12, preferably 12.5
The reaction is performed under the condition of 14.5, which is 0.03 to 3N in terms of alkali normality.
（実施例） 貴金属を含有するヨウ素エッチング廃液（金:5.8g/
、遊離ヨウ素としての酸化還元規定度 :0.15N、総ヨウ素濃度:180g/、pH＝7.8）100に水酸
化ナトリウムのフレークを撹拌しながら3kg投入してpH1
3.6としたところ、黒色の廃液が淡黄色となるとともに
金が析出した。30分間の撹拌後、１時間静置し上澄みの
金濃度を分析したところ、まだ0.36g/の金が溶けてい
たので、さらに亜鉛末を250g加えてよく撹拌した。水素
ガスの発生とともに金が析出し、約１時間後に撹拌を止
めてさらに１時間静置した。廃液の液色は透明になって
おり、上澄み液を分析したところ金が検出されなかった
ので、金を濾過により分離して回収した。(Example) Iodine etching waste liquid containing noble metal (gold: 5.8 g /
, Redox normality as free iodine: 0.15N, total iodine concentration: 180g /, pH = 7.8)
At 3.6, the black waste liquid became pale yellow and gold was deposited. After stirring for 30 minutes, the mixture was allowed to stand for 1 hour, and the gold concentration of the supernatant was analyzed. Since 0.36 g / gold was still dissolved, 250 g of zinc powder was further added and the mixture was stirred well. Gold was deposited with the generation of hydrogen gas, and after about 1 hour, stirring was stopped and the mixture was left still for 1 hour. The liquid color of the waste liquid was transparent, and no gold was detected when the supernatant was analyzed. Therefore, the gold was separated by filtration and collected.
析出した金は洗浄乾燥し分析したところ、総重量で58
5.2gあり、金が99.3％、亜鉛等の不純物が0.7％含まれ
ており、金として581.3gが回収された。The deposited gold was washed, dried and analyzed, and the total weight was 58%.
There was 5.2 g, which contained 99.3% of gold and 0.7% of impurities such as zinc, and 581.3 g of gold was recovered.
従来は、当該貴金属廃液中の遊離ヨウ素を分解するた
めの酸化還元当量（0.15N×100＝15当量）と金を析出
させるのに必要な酸化還元当量5.8g/×100÷197×
３＝8.8当量）を合計した23.8当量を必要としたが、本
実施例では亜鉛末として加えた7.6当量を使用したにす
ぎなかった。Conventionally, a redox equivalent (0.15N x 100 = 15 equivalents) for decomposing free iodine in the noble metal waste liquid and a redox equivalent 5.8 g / x100 / 197x required for depositing gold
3 = 8.8 equivalents), which required 23.8 equivalents, but in this example, only 7.6 equivalents added as zinc dust were used.
但し197は金の分子量、３は金１モルの当量である。 Where 197 is the molecular weight of gold and 3 is the equivalent of 1 mole of gold.
（従来例１） 貴金属を含有するヨウ素エッチング廃液（金:5.8g/
、遊離ヨウ素としての酸化還元規定度 :0.15N、総ヨウ素濃度:180/、pH＝7.8）100に加水
ヒドラジンを入れて貴金属を還元した。遊離ヨウ素を分
解するに必要な酸化還元当量の15当量（0.15N×100＝
15当量）と金を回収するために必要な8.8当量（5.8/
×100÷197×３＝8.8当量）とを合計した23.8当量の
1.1倍量に相当する26.2当量の加水ヒドラジンを加えた
にもかかわらず金を金で還元することができなかったの
で、さらに6.55当量を加えて当該貴金属を含有するヨウ
素エッチング廃液中の金を還元、析出させた。(Conventional example 1) Iodine etching waste liquid containing noble metal (gold: 5.8 g /
The normality of redox as free iodine: 0.15N, total iodine concentration: 180 /, pH = 7.8) 100 was added with hydrazine hydrolyzate to reduce noble metals. 15 equivalents of redox equivalents required to decompose free iodine (0.15N x 100 =
15 equivalents) and 8.8 equivalents (5.8 /
× 100 ÷ 197 × 3 = 8.8 equivalents) and 23.8 equivalents
Even though 26.2 equivalents of hydrohydrazine equivalent to 1.1 times were added, gold could not be reduced with gold, so an additional 6.55 equivalent was added to reduce gold in the iodine etching waste liquid containing the noble metal. Was deposited.
金を回収するのに使用した加水ヒドラジンの量は、3
2.75当量であり、実施例１の4.3倍の還元剤を使用し
た。The amount of hydrazine hydrate used to recover the gold was 3
2.75 equivalents, and 4.3 times the reducing agent of Example 1 was used.
（実施例２） ヨウ素を含む貴金属含有廃液（金:12.5g/、銀1.2g/
、パラジウム2.6g/、白金0.4g/、pH＝5.5）10
に水酸化カリウムを加えてpH13.0にしたところ一部の金
が析出した。さらにこの液を、陽極に10cm×20cmの白金
メッキしたチタン板、陰極に10cm×20cmのステンレス板
（SUS316）を使用して、10Aで４時間電解して、陰極に
貴金属を析出させた。電解中に液のpHが下がったので水
酸化カリウムでpHを13.2に調整した。(Example 2) Noble metal-containing waste liquid containing iodine (gold: 12.5 g /, silver: 1.2 g /
, 2.6 g / palladium, 0.4 g / platinum, pH = 5.5) 10
When potassium hydroxide was added to the mixture to adjust the pH to 13.0, some gold was precipitated. Further, this solution was electrolyzed at 10 A for 4 hours using a 10 cm × 20 cm platinum-plated titanium plate for the anode and a 10 cm × 20 cm stainless steel plate (SUS316) for the cathode to deposit a noble metal on the cathode. Since the pH of the solution dropped during electrolysis, the pH was adjusted to 13.2 with potassium hydroxide.
陰極に析出した貴金属を分析したところ、金が11.8
g、銀が9.5g、パラジウムが24.8g、白金が3.9gふくまれ
ていたが他の重金属はほとんど含まれていなかった。Analysis of the noble metal deposited on the cathode revealed that gold was 11.8
g, silver 9.5 g, palladium 24.8 g, and platinum 3.9 g but contained little other heavy metals.
（従来例２） コウ素を含む貴金属含有廃液（金:12.5g/，銀1.2g/
、パラジウム2.6g/、白金0.4g/、pH＝5.5）５
を、陽極と陰極に10cm×20cmの白金メッキしたチタン板
を使用して、10Aで４時間電解したところ、貴金属が析
出するものの、一端析出した貴金属が電極より剥離して
再び液中に溶解してしまうので、貴金属を回収すること
はできなかった。(Conventional example 2) Waste liquid containing noble metal containing iodine (gold: 12.5 g /, silver: 1.2 g /
, 2.6 g / palladium, 0.4 g / platinum, pH = 5.5) 5
Was electrolyzed at 10 A for 4 hours using a 10 cm x 20 cm platinum-plated titanium plate for the anode and cathode, but the noble metal was deposited, but the noble metal once deposited was separated from the electrode and dissolved again in the liquid. So no precious metals could be recovered.
（発明の効果） 本発明はヨウ素を含む貴金属含有廃液より貴金属を回
収するに際し、まずヨウ素を含む貴金属含有廃液のpHを
12以上の強アルカリ性として該貴金属含有廃液中の遊離
ヨウ素成分を、ヨウ素イオンとヨウ素酸イオンに不均化
され、さらに化学還元剤及び／または／電解による残る
貴金属を析出させることにより貴金属を回収できるよう
にしている。強アルカリ性にて反応させることにより、
従来ように貴金属の回収に多量の還元剤を必要としなく
なるという効果がある。この結果、回収、精製にかかる
コストが大幅に改善され、貴金属のように稀少な金属を
回収するうえで、産業への貢献大なるものといえる。(Effect of the Invention) In the present invention, when recovering a noble metal from a noble metal-containing waste liquid containing iodine, first, the pH of the noble metal-containing waste liquid containing iodine is adjusted.
The free iodine component in the noble metal-containing waste liquid is disproportionated to iodine ion and iodate ion as a strong alkali of 12 or more, and the noble metal can be recovered by precipitating the remaining noble metal by a chemical reducing agent and / or / electrolysis. Like that. By reacting with strong alkali,
There is an effect that a large amount of a reducing agent is not required for recovery of a noble metal as conventionally. As a result, the cost for recovery and purification is greatly improved, and it can be said that the recovery of rare metals such as noble metals greatly contributes to the industry.
Claims (1)
属を回収するに際し、該遊離ヨウ素を含む貴金属含有廃
液のpHを12以上の強アルカリ性として該遊離ヨウ素をヨ
ウ素酸イオンに変換した後、化学還元剤及び／または電
解により貴金属を析出させ貴金属を回収することを特徴
とする貴金属の回収方法。When recovering a noble metal from a noble metal-containing waste liquid containing free iodine, the pH of the noble metal-containing waste liquid containing free iodine is adjusted to a strong alkalinity of 12 or more to convert the free iodine into iodate ions. A method for recovering a noble metal, comprising: precipitating a noble metal by an agent and / or electrolysis to recover the noble metal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP409088A JP2619892B2 (en) | 1988-01-12 | 1988-01-12 | Precious metal recovery method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP409088A JP2619892B2 (en) | 1988-01-12 | 1988-01-12 | Precious metal recovery method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01180922A JPH01180922A (en) | 1989-07-18 |
| JP2619892B2 true JP2619892B2 (en) | 1997-06-11 |
Family
ID=11575095
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP409088A Expired - Lifetime JP2619892B2 (en) | 1988-01-12 | 1988-01-12 | Precious metal recovery method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2619892B2 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3957505A (en) * | 1974-08-05 | 1976-05-18 | Bayside Refining And Chemical Company | Gold reclamation process |
| GB1533477A (en) * | 1976-05-25 | 1978-11-22 | Automated Med Syst | Removal of heavy metals from solution |
| JPS589129B2 (en) * | 1979-11-02 | 1983-02-19 | 三菱化学株式会社 | How to recover rhodium |
| JPS58174532A (en) * | 1982-04-05 | 1983-10-13 | Tanaka Kikinzoku Kogyo Kk | Recovery of palladium or noble metal mixed in palladium |
-
1988
- 1988-01-12 JP JP409088A patent/JP2619892B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01180922A (en) | 1989-07-18 |
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